润色调压是通过变压器的分接开关切换改变变压器高压侧绕组匝数从而改变其变比实现电压的调整。切换方式有两种：一种是不带电切换称为无激磁调压调整范围通常在以内；另一种是带负荷切换称为有载调压调整范围可达但结构复杂、价格昂贵只有在两种情况下才予以选用：接于出力变化大的发电厂的主变压器特别是潮流方向不固定且要求变压器二次电压维持在一定水平时；接于时而为送端时而为受端具有可逆工作特点的联络变压器为保证供电质量

Voltage regulation is achieved by switching the tap changer of a transformer, changing the number of turns on the high voltage side of the transformer, and thereby changing its voltage ratio to adjust the voltage. There are two ways to switch: one is non-energized switching, called no-load voltage regulation, with an adjustment range usually within ±10%; the other is load switching, called on-load voltage regulation, with an adjustment range of up to ±15%, but with a complex structure and high price, and only used in two situations: connected to the main transformer of a power plant with large output changes, especially when the flow direction is not fixed, and when the secondary voltage of the transformer needs to be maintained at a certain level; connected to a coupling transformer with reversible working characteristics, sometimes as a sending end and sometimes as a receiving end, to ensure constant bus voltage.

Usually, on-load voltage regulation is rarely used in the main transformer of a power plant, because voltage regulation can be achieved by adjusting the excitation of the generator, and no-load voltage regulation is generally used